TBB: add support to include certificates in a FIP image

This patch extends the FIP tool to include the certificates
generated by the 'cert_create' tool.

If GENERATE_COT build option is enabled, the Makefile adds the
certificates as dependencies to create the FIP file. Thus, make
target 'fip' will also build the certificates as part of the
Trusted Firmware build process.

Change-Id: I5eee500da7f7be6cfb6e3df0423599739d260074
diff --git a/tools/fip_create/fip_create.h b/tools/fip_create/fip_create.h
index ef321cd..3258335 100644
--- a/tools/fip_create/fip_create.h
+++ b/tools/fip_create/fip_create.h
@@ -34,7 +34,7 @@
 #include <stdint.h>
 #include <uuid.h>
 
-#define MAX_FILES			10
+#define MAX_FILES			20
 
 /* TODO: Update this number as required */
 #define TOC_HEADER_SERIAL_NUMBER	0x12345678